On Wed, Jan 03, 2024 at 08:41:15AM +0000, Christoph Hellwig wrote:
> vfs_getattr is needed to query inode attributes for unknown underlying
> file systems. But shmemfs is well known for users of shmem_file_setup
> and shmem_read_mapping_page_gfp that rely on it not needing specific
> inode revalidation and having a normal mapping. Remove the detour
> through the getattr method and an extra wrapper, and just read the
> inode size and i_bytes directly in the scrub tracing code.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/scrub/trace.h | 34 ++++++++++------------------------
> fs/xfs/scrub/xfile.c | 19 -------------------
> fs/xfs/scrub/xfile.h | 7 -------
> 3 files changed, 10 insertions(+), 50 deletions(-)
>
> diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
> index 6bbb4e8639dca6..ed9e044f6d603c 100644
> --- a/fs/xfs/scrub/trace.h
> +++ b/fs/xfs/scrub/trace.h
> @@ -861,18 +861,11 @@ TRACE_EVENT(xfile_destroy,
> __field(loff_t, size)
> ),
> TP_fast_assign(
> - struct xfile_stat statbuf;
> - int ret;
> -
> - ret = xfile_stat(xf, &statbuf);
> - if (!ret) {
> - __entry->bytes = statbuf.bytes;
> - __entry->size = statbuf.size;
> - } else {
> - __entry->bytes = -1;
> - __entry->size = -1;
> - }
> - __entry->ino = file_inode(xf->file)->i_ino;
> + struct inode *inode = file_inode(xf->file);
> +
> + __entry->ino = inode->i_ino;
> + __entry->bytes = inode->i_bytes;
Shouldn't this be (i_blocks << 9) + i_bytes?
> + __entry->size = i_size_read(inode);
> ),
> TP_printk("xfino 0x%lx mem_bytes 0x%llx isize 0x%llx",
> __entry->ino,
> @@ -891,19 +884,12 @@ DECLARE_EVENT_CLASS(xfile_class,
> __field(unsigned long long, bytecount)
> ),
> TP_fast_assign(
> - struct xfile_stat statbuf;
> - int ret;
> -
> - ret = xfile_stat(xf, &statbuf);
> - if (!ret) {
> - __entry->bytes_used = statbuf.bytes;
> - __entry->size = statbuf.size;
> - } else {
> - __entry->bytes_used = -1;
> - __entry->size = -1;
> - }
> - __entry->ino = file_inode(xf->file)->i_ino;
> + struct inode *inode = file_inode(xf->file);
> +
> + __entry->ino = inode->i_ino;
> + __entry->bytes_used = inode->i_bytes;
Here too.
> __entry->pos = pos;
> + __entry->size = i_size_read(inode);
> __entry->bytecount = bytecount;
> ),
> TP_printk("xfino 0x%lx mem_bytes 0x%llx pos 0x%llx bytecount 0x%llx isize 0x%llx",
> diff --git a/fs/xfs/scrub/xfile.c b/fs/xfs/scrub/xfile.c
> index 090c3ead43fdf1..87654cdd5ac6f9 100644
> --- a/fs/xfs/scrub/xfile.c
> +++ b/fs/xfs/scrub/xfile.c
> @@ -291,25 +291,6 @@ xfile_seek_data(
> return ret;
> }
>
> -/* Query stat information for an xfile. */
> -int
> -xfile_stat(
> - struct xfile *xf,
> - struct xfile_stat *statbuf)
> -{
> - struct kstat ks;
> - int error;
> -
> - error = vfs_getattr_nosec(&xf->file->f_path, &ks,
> - STATX_SIZE | STATX_BLOCKS, AT_STATX_DONT_SYNC);
> - if (error)
> - return error;
> -
> - statbuf->size = ks.size;
> - statbuf->bytes = ks.blocks << SECTOR_SHIFT;
> - return 0;
> -}
> -
> /*
> * Grab the (locked) page for a memory object. The object cannot span a page
> * boundary. Returns 0 (and a locked page) if successful, -ENOTBLK if we
> diff --git a/fs/xfs/scrub/xfile.h b/fs/xfs/scrub/xfile.h
> index d56643b0f429e1..c602d11560d8ee 100644
> --- a/fs/xfs/scrub/xfile.h
> +++ b/fs/xfs/scrub/xfile.h
> @@ -63,13 +63,6 @@ xfile_obj_store(struct xfile *xf, const void *buf, size_t count, loff_t pos)
>
> loff_t xfile_seek_data(struct xfile *xf, loff_t pos);
>
> -struct xfile_stat {
> - loff_t size;
> - unsigned long long bytes;
> -};
> -
> -int xfile_stat(struct xfile *xf, struct xfile_stat *statbuf);
Removing this function will put some distance between the kernel and
xfsprogs xfile implementations, since userspace can't do failure-free
fstat. OTOH I guess if xfile_stat fails in userspace, our xfile is
screwed and we probably have to abort the whole program anyway.
For the kernel I like getting rid of this clutter, modulo the question
above.
--D
> -
> int xfile_get_page(struct xfile *xf, loff_t offset, unsigned int len,
> struct xfile_page *xbuf);
> int xfile_put_page(struct xfile *xf, struct xfile_page *xbuf);
> --
> 2.39.2
>
>
